This invention relates to an organic EL (Electro-Luminescent) device and a various electronic apparatus employing the organic EL device.
As disclosed in Patent Document 1, this kind of organic EL device has, for example, an organic EL element as a luminescent element in each pixel in the image display region on a substrate. An organic EL element consists of anodes formed for every pixel, a cathode opposite to a plurality of anodes, and an organic EL layer interposed therebetween. In a peripheral region located around the image display region, there are a plurality of signal lines serving as a supply path of a driving signal for driving each pixel, and a cathode wiring line connected to the cathode of the organic EL element. According to the technique described in Patent Document 1, the cathode is electrically connected to a cathode wiring line formed below the cathode on a substrate with interposing a supplemental electrode in a connecting region located along one side of the image display region (see FIGS. 1(c) and 2 in Patent Document 1).
[Patent Document 1] Japan Unexamined Patent Application Publication No. 2003-288994.
In the case a plurality of signal lines are arranged under the cathode wiring line in the peripheral region on the substrate, as shown in the connecting region disclosed in Patent Document 1, a step could occur on the surface of the region where the cathode wiring line contacts with the cathode since the signal lines are arranged right under the contact area. This step causes an unfavorable influence in a protecting layer coating process and its etching process onto the surface of the contact area of the cathode wiring line at the time of manufacturing organic EL devices. That is, this step on the surface of the cathode wiring line can deteriorate the coating coverage of a protecting layer or an unnecessary area can be subject to erosion by etching. In this case, the manufacturing yield of the organic EL device may falls or the electrical connection between the cathode wiring line and the cathode may deteriorate to cause a malfunction. Moreover, such step makes the thickness of the cathode wiring line uneven. The uneven layer thickness makes resistance distribution uneven which causes current to be accumulated on a specific region with a low resistance to cause the organic EL device deteriorated. As the result, reliability on the organic EL device goes down.
On the other hand, when the area of the contact region is increased in order to ensure an enough capacity in the contact area of the cathode wiring line, the peripheral region is also increased and the size of the substrate should be enlarged, thus making difficult to miniaturize the organic EL device.
Under the reflection of these problems, the object of the present invention is to provide an organic EL device with a good electrical connection between the cathode wiring line and the cathode, a compact size, and a high reliability, and an electronic device employing such organic EL device.